Textual representation of IPv6 address used as input to methods
takes one of the following forms:

The preferred form is x:x:x:x:x:x:x:x,
where the 'x's are
the hexadecimal values of the eight 16-bit pieces of the
address. This is the full form. For example,

1080:0:0:0:8:800:200C:417A

Note that it is not necessary to write the leading zeros in
an individual field. However, there must be at least one numeral
in every field, except as described below.

Due to some methods of allocating certain styles of IPv6
addresses, it will be common for addresses to contain long
strings of zero bits. In order to make writing addresses
containing zero bits easier, a special syntax is available to
compress the zeros. The use of "::" indicates multiple groups
of 16-bits of zeros. The "::" can only appear once in an address.
The "::" can also be used to compress the leading and/or trailing
zeros in an address. For example,

1080::8:800:200C:417A

An alternative form that is sometimes more convenient
when dealing with a mixed environment of IPv4 and IPv6 nodes is
x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values
of the six high-order 16-bit pieces of the address, and the 'd's
are the decimal values of the four low-order 8-bit pieces of the
standard IPv4 representation address, for example,

::FFFF:129.144.52.38

::129.144.52.38

where "::FFFF:d.d.d.d" and "::d.d.d.d" are, respectively, the
general forms of an IPv4-mapped IPv6 address and an
IPv4-compatible IPv6 address. Note that the IPv4 portion must be
in the "d.d.d.d" form. The following forms are invalid:

::FFFF:d.d.d

::FFFF:d.d

::d.d.d

::d.d

The following form:

::FFFF:d

is valid, however it is an unconventional representation of
the IPv4-compatible IPv6 address,

::255.255.0.d

while "::d" corresponds to the general IPv6 address
"0:0:0:0:0:0:0:d".

For methods that return a textual representation as output
value, the full form is used. Inet6Address will return the full
form because it is unambiguous when used in combination with other
textual data.

Special IPv6 address

IPv4-mapped address

Of the form::ffff:w.x.y.z, this IPv6 address is used to
represent an IPv4 address. It allows the native program to
use the same address data structure and also the same
socket when communicating with both IPv4 and IPv6 nodes.

In InetAddress and Inet6Address, it is used for internal
representation; it has no functional role. Java will never
return an IPv4-mapped address. These classes can take an
IPv4-mapped address as input, both in byte array and text
representation. However, it will be converted into an IPv4
address.

The textual representation of IPv6 addresses as described above can be
extended to specify IPv6 scoped addresses. This extension to the basic
addressing architecture is described in [draft-ietf-ipngwg-scoping-arch-04.txt].

Because link-local and site-local addresses are non-global, it is possible
that different hosts may have the same destination address and may be
reachable through different interfaces on the same originating system. In
this case, the originating system is said to be connected to multiple zones
of the same scope. In order to disambiguate which is the intended destination
zone, it is possible to append a zone identifier (or scope_id) to an
IPv6 address.

The general format for specifying the scope_id is the following:

IPv6-address%scope_id

The IPv6-address is a literal IPv6 address as described above.
The scope_id refers to an interface on the local system, and it can be
specified in two ways.

As a numeric identifier. This must be a positive integer
that identifies the particular interface and scope as understood by the
system. Usually, the numeric values can be determined through administration
tools on the system. Each interface may have multiple values, one for each
scope. If the scope is unspecified, then the default value used is zero.

As a string. This must be the exact string that is returned by
NetworkInterface.getName() for the particular interface in
question. When an Inet6Address is created in this way, the numeric scope-id
is determined at the time the object is created by querying the relevant
NetworkInterface.

Note also, that the numeric scope_id can be retrieved from
Inet6Address instances returned from the NetworkInterface class. This can be
used to find out the current scope ids configured on the system.

Create an Inet6Address in the exact manner of InetAddress.getByAddress(String,byte[]) except that the IPv6 scope_id is
set to the value corresponding to the given interface for the address
type specified in addr.

Method Detail

getByAddress

Create an Inet6Address in the exact manner of InetAddress.getByAddress(String,byte[]) except that the IPv6 scope_id is
set to the value corresponding to the given interface for the address
type specified in addr. The call will fail with an
UnknownHostException if the given interface does not have a numeric
scope_id assigned for the given address type (eg. link-local or site-local).
See here for a description of IPv6
scoped addresses.

Parameters:

host - the specified host

addr - the raw IP address in network byte order

nif - an interface this address must be associated with.

Returns:

an Inet6Address object created from the raw IP address.

Throws:

UnknownHostException - if IP address is of illegal length, or if the interface does not
have a numeric scope_id assigned for the given address type.

Since:

1.5

getByAddress

Create an Inet6Address in the exact manner of InetAddress.getByAddress(String,byte[]) except that the IPv6 scope_id is
set to the given numeric value. The scope_id is not checked to determine
if it corresponds to any interface on the system.
See here for a description of IPv6
scoped addresses.

getHostAddress

Returns the IP address string in textual presentation. If the instance
was created specifying a scope identifier then the scope id is appended
to the IP address preceded by a "%" (per-cent) character. This can be
either a numeric value or a string, depending on which was used to create
the instance.

equals

Compares this object against the specified object. The result is true if and only if the argument is not null and it represents
the same IP address as this object.

Two instances of InetAddress represent the same IP address
if the length of the byte arrays returned by getAddress is the
same for both, and each of the array components is the same for the byte
arrays.